Grommets may be used to accommodate fasteners passing through a cover member. For applications which require relatively high load bearing capability, such as when grommets are used for providing locations for bolts or studs to attach a cover member to a firewall of a motor vehicle, grommets are conventionally formed as single pieces of metal. Metal is the material of choice due to its high strength. Such grommets are usually cast, wrought, extruded, or forged, and then machined to obtain the desired final shape and finish. Because of the multiple manufacturing steps, however, such grommets are costly to manufacture. Conventional grommets are also relatively heavy, and do not attenuate sound or vibrations that may emanate from a source such as an engine.
Furthermore, because conventional grommets are single pieces which are inserted into openings in a cover member, modifications are typically required to the cover member in order to facilitate insertion of the grommets. These modifications may include tapering the cover member around the edges of the openings. Such modifications, however, reduce the strength of the cover member around the edges of the openings, and reduce the noise attenuation capability of the cover member. In addition, the grommets typically fit loosely in the cover member and, therefore, the grommets can be easily displaced during handling and assembly.